1. Field of Invention
The present invention relates to a serial controller and a bi-directional serial controller, and more particularly to a serial controller and a bi-directional serial controller for synchronously transmitting data signals at all stages in a series with an inverted clock.
2. Related Art
In recent years, with the raising of the worldwide issue of energy-saving and reducing CO2 emission, in the design of architectural outdoor illumination, decorative illumination, or scenario illumination for commercial purposes, light-emitting diodes (LEDs) are more widely used as illumination apparatus. For example, since the RGB cluster formed by red, blue, and green LEDs has diversified light and shadow changing effects, the RGB cluster is usually connected in series for different illuminators so as to form a strip screen, curtain display, or wall washer light of multilevel serial spot lights, which is applied in the long-distance light string.
Since this kind of illumination apparatus is usually designed according to the appearance of the building or different commercial requirements, when the range of appearance of the building demanding for illumination is large or the design of the illuminator is complicated, the designer needs to connect in series a large number of spot lights, LEDs, and the driving clocks thereof so as to form a long string of RGB cluster, thereby achieving a better illumination effect.
However, the problem of this serial RGB cluster lies in that the driving clock for driving the spot lights at each stage in the series is not a single global signal. That is to say, the driving clock of the spot lights at each stage is obtained from the driving clock of the spot lights in the previous stage. Therefore, regarding the signal of the driving clock at one stage in the series, when the duty cycle of the driving clock offsets due to the capacitance effect or accumulative effect generated in the transmission distance, e.g., the time of the signal of the driving clock at the high level is unequal to the time of the signal at the low level, and in this circumstance, for the serial RGB cluster formed by connecting multilevel spot lights in series, the signal waveform of the driving clock of the spot lights at the latter level is severely distorted due to the multilevel accumulative effect.
Moreover, since the distance between the spot lights at each stage is quite long in the serial RGB cluster, if errors occur to the driving circuit for driving the spot lights or to the LED of the spot lights at a certain stage, the data signal must be pulled back to the spot lights at the 1st stage from the spot lights at the last stage, for carrying out the error detection. This method not only reduces the error detection efficiency of the serial RGB cluster, but also as abovementioned causes the waveform distortion of the driving clock.